Here's a description for an OR tourniquet:
A standard football or bicycle pump can be used for inflation. With a little imagination a manometer can be palced in the system using a 3-way stopcock will all 3 ways opened.Link
After the correct pressure is obtained while pumping, the tube going to the tourniquet proper is clamped securely. The pressure that you set will be maintained quite well as long as the tourniquet has no leaks and the clamp is tight enough. A rechargeable cordless drill can be gas sterilized after proper charging and used on low speed (to prevent burning of the bone) for orthopedic cases requiring a lot of drilling such as external fixator placement. An assortmnet of drill bits from the hardware store is helpful.